Transmission of leprosy in nude mice.

Nude mice in groups of 10 were exposed to M. leprae by subcutaneous injection and topically through the nose, lungs, mouth, stomach and skin, broken and unbroken. Animals injected subcutaneously and those topically exposed to M. leprae through the nose developed localized disease which in the course of time became generalized. The nose seems to be the site of entry of M. leprae in this model. To the extent that these results can be generalized to humans exposed to M. leprae, it would seem that leprosy bacilli impact topically on the nasal mucosa or are inoculated subcutaneously.